1. Field of the Invention
Embodiments of the present disclosure relate generally to DC-DC power conversion, and, in particular, to lossless commutation during DC-DC power conversion.
2. Description of the Related Art
Electronic switch-mode DC-DC converters convert one DC voltage level to another by transferring energy through a storage medium. Some switch-mode DC-DC converters, such as flyback converters, utilize transformers to perform such energy storage. In a flyback converter, energy is stored in a primary winding of the transformer during a first period when a current control switch is activated to allow current flow through the primary winding, and the stored energy is then transferred to a secondary winding of the transformer during a second period when the current control switch is deactivated.
During operation of the flyback converter, current flowing in the primary winding produces a magnetic flux that is coupled to the secondary winding. The magnetic flux also traverses paths in between the windings, resulting in leakage inductance in the transformer. Such leakage inductance is a property of the transformer where the windings of the transformer appear to have some self inductance in series with each winding. The energy stored in the leakage inductance cannot be transferred to the secondary winding and is therefore wasted. Additionally, when the current control switch is deactivated, the leakage inductance causes the voltage across the current control switch to ring, resulting in a sharp voltage peak across the switch and potentially damaging the switch. To mitigate this risk, high cost switches must be employed.
Therefore, there is a need in the art for a method and apparatus for more efficiently operating a DC-DC converter.